Apparatus for drilling and maintenance of holes in a golf course The invention relates to an apparatus for drilling and maintaining holes in golf course greens, where new holes are cut at regular intervals and the used (old) holes they are replacing are plugged The work is usually performed at intervals of a few days. The apparatus is of the type that is built onto a mini-tractor (lawn tractor or similar mobile mini-tractor unit), with the drilling unit itself suspended in a hydraulic hoist for moving the unit up and down between a raised transport position and a lowered drilling position. The drilling unit is equipped with a downward directed hollow auger, which is operated by the tractor via its hydraulic or mechanical power take-off.
The golf course holes are in so-called greens, viz. very smooth, closely mown areas of high-quality grass. The holes--there is one in each green--have a diameter of 108 mm and a depth of exactly 175 mm. The holes must have a well-defined, sharp edge (rim) to achieve a completely neutral effect on a rolling ball, so that the ball neither encounters resistance at the rim of the hole nor gets pulled in towards the hole by a "funnel effect". For obvious reasons, both greens and holes are of vital importance to the game because the concluding strokes take place on the green.
As the holes are situated in the grass's growth zone, the grass at the rim of the hole withers relatively quickly (in the growth period within about 1 day). At the same time, the heavier traffic just around the hole means that the grass gets trampled and worn in a relatively small area around the hole. This can naturally not be accepted, so it is necessary to maintain the holes at regular intervals (daily in the high season) and to cut new, sharp-rimmed holes and at the same time plug the old holes in order to spread the traffic and thus also the wear over a larger area of the green. The old holes are plugged with the turf removed from the new holes. As each hole is plugged it is trodden down with a foot to achieve a smooth surface.
The work can be done manually with a special hollow auger equipped with a long handle with a transverse grip. However, doing the job manually is both time-consuming and fatiguing. For this reason and because of a general need to rationalise the operation of golf courses, machines and various types of aids have been developed for the maintenance work described.
One example of such an aid is known from U.S. Pat. No. 4,836,294, which relates to a tractor-mounted drilling machine for cutting holes in golf course greens. The drilling machine is suspended in a lift-like hoisting arrangement mounted on the back of a mini-tractor of the type typically used for mowing grass at golf courses and other maintenance work. The drilling unit, which is operated by the tractor's motor via a hydraulic power outlet, is suspended, vertically adjustable in relation to the tractor, in a first frame. The auger itself is bedded in a second frame, the angle of which can be adjusted in relation to the first frame by turning it around a horizontal axis. This means that the auger can be put into an exactly vertical position regardless of the slope of the ground. During cutting, the auger rotates around its own axis, under the action of a hydraulic motor. The auger is a hollow auger, i.e. like a piece of pipe with a cutting edge at the bottom. Inside it there is a device for ejecting the removed turf core.
As mentioned the removed turf core is placed in the old hole. The procedure here is as follows: After cutting a new hole the tractor is manoeuvred back to the old hole, where the drilling unit is positioned exactly over the hole. The auger is moved into the vertical position, and only then can the auger with the core be pressed down in the hole and the core released The whole procedure is tedious and time-consuming, and, in practice, the necessary positioning and alignment of the auger in relation to the existing (old) hole causes a lot of problems. If the auger is pressed into the hole crookedly or a little to one side, the hole gets deformed and it becomes very difficult to tread the turf core properly into place so that it is completely flush with the surface of the grass. For obvious reasons this is an absolute requirement.